In the past, an one-dimensional nanowire has received attention from many researchers because of an importance of scientific researches started with distinctive electrical, physical, and chemical properties as well as applicability for various next generation nano-devices such as a high-tech electronic device, a biochemical sensor, an optoelectronic device, a future energy device, and the like. As a result, a technology capable of manufacturing various materials and forms of nanowires has been intensively explored. Particularly, a structure in which the nanowires are aligned in an array form at any angle for a surface of a substrate having a large area provides an opportunity capable of increasing an aspect ratio and a degree of integration of the nanowire, such that a specific surface area of the nanowire may be maximally utilized and efficiency of the nano-device may be increased. Therefore, an effort for manufacturing a nanowire-based device having the above-mentioned structure has been recently made.
Additionally, in order to put the nanowire-based device to practical use, physical and chemical properties of each of the nanowires aligned on the large area are effectively collected, such that proper performance of a device should be implemented. To this end, a development of a technology that all nanowires aligned on the surface of the substrate having the large area may be uniformly and stably in contact with lower and upper electrodes and may be integrated should be preceded. In addition, a technology capable of efficiently analyzing and evaluating property of the device should also be developed. However, it is difficult to grow the nanowire array having a high degree of integration in a uniform length on the large area using the related art. As well, there is also a technical limit in forming a reliable electrode on the nanowire array. For this reason, in order to manufacture a device using the nanowires so far, a method of patterning the electrode by a lithography process to thereby make contact with the nanowires dispersed in parallel on the substrate has been mainly used. In recent, a report that an electrode contact of the nanowires is formed by selectively growing the nanowire on the upper and lower electrodes in a bridge form which is pre-formed using a lithography has been proposed. However, the above-mentioned method has a complex manufacturing process and high cost as well as a limit in the degree of integration.
A method which was most widely used is a method in which only a tip portion of the nanowire is selectively exposed to thereby form a contact with a desired metal or semiconductor material by molding a polymeric insulator on the nanowire array grown on the substrate and then etching the polymer by an oxygen plasma process. However, in the above-mentioned method, since the entire nanowire surfaces are completely coated with the polymeric material, it is difficult to apply as a sensor and a high-tech nano-device such as the optoelectronic device utilizing the large specific surface area of the nanowire. In addition, in the case in which the aspect ratio of the nanowire array is increased, since the nanowires are bound with each other in the polymeric molding process and the aligned structure is destroyed, it is difficult to apply the above-mentioned processes.
Therefore, in order to put the nanowire-based device to practical use, a technology capable of economically manufacturing the extended arrays of nanowires with high aspect ratio and a technology of forming the upper and lower electrodes having excellent reliability without loss of the large specific surface area of the nanowire array need to be developed.
The related art relating thereto is disclosed in Korean Patent Laid-Open Publication No. 2012-0010465 (entitled “Method of Arranging Nanowires).